please answer this:
A fluid system at a temperature of 60 °C and pressure of 90x103 N/M2 executes a reversible process during which the temperature of the system remains constant. The heat transfer to the fluid is 120 kJ. Determine the increase in entropy.
Answers
1
The First Law of Thermodynamics: Closed Systems
The first law of thermodynamics can be simply stated as follows: during an interaction
between a system and its surroundings, the amount of energy gained by the system must
be exactly equal to the amount of energy lost by the surroundings.
A closed system can exchange energy with its surroundings through heat and work
transfer. In other words, work and heat are the forms that energy can be transferred
across the system boundary.
Based on kinetic theory, heat is defined as the energy associated with the random
motions of atoms and molecules.
Heat Transfer
Heat is defined as the form of energy that is transferred between two systems by virtue of
a temperature difference.
Note: there cannot be any heat transfer between two systems that are at the same
temperature.
Note: It is the thermal (internal) energy that can be stored in a system. Heat is a form of
energy in transition and as a result can only be identified at the system boundary.
Heat has energy units kJ (or BTU). Rate of heat transfer is the amount of heat transferred
per unit time.
Heat is a directional (or vector) quantity; thus, it has magnitude, direction and point of
action.
Notation:
– Q (kJ) amount of heat transfer
– Q° (kW) rate of heat transfer (power)
– q (kJ/kg) ‐ heat transfer per unit mass
– q° (kW/kg) ‐ power per unit mass
Sign convention: Heat Transfer to a system is positive, and heat transfer from a system is
negative. It means any heat transfer that increases the energy of a system is positive, and
heat transfer that decreases the energy of a system is negative.